I have a 1998 Ranger XLT 4.0L with 119,000 miles.
I'm having an awful time keeping my truck started. I had been having this trouble everyone once and a while and after restarting it a few times it would go away. Now it happens every time I try to start my truck. It will crank and then shut right back off. The only way I can get it going it to baby throttle to keep the engine running. When I pull up to a traffic light the RPMs will immediately go to around 300-400 RPMs, just as if the engine it barely hanging on to life. I thought this may be the throttle position sensor. Any ideas? I'm NOT get a "check engine" light.

 

Try cleaning the IAC/idle air control valve.

Sometimes cleaning works , sometimes not.

 

Where is that at?

 

Pull the large tube from the air cleaner off of the throttle body. Look in there & you'll see the throttle plate.

The IAC bleeds air around the throttle plate when your foot is off the gas & the throttle plate is closed.

 

I was going to post a link for you ,but my computer is acting all stupid & wont let me do a search.

Try this, at the top of the Ranger forum click on "read first ranger tech info" Scroll down & click on "4.0L idle air control valve."

 

I agree, definitely Idle air control valve.

 

I too like the IAC idea.
Here is the Tech Info link, with a picture of the IAC.
https://www.ford-trucks.com/forums/1...rol-valve.html

The IAC is famous for making a whoooo noise, & the computer uses it to control engine idle speed, so if it acts out, we have idle problems. It's a common problem part.

It's mounted on the intake air tube just ahead of the throttle body. It's viewable with the hood raised, from the drivers side of the engine bay.

If you decide to remove & clean it, use a plastic safe cleaner like CRC QD, or MAF spray cleaner & lint free foam swabs.

Cleaning mine didn't last, but was a good trouble shooting step for me.

Let us know how it goes.

 

Would this also cause the engine to not want to start at all after the first "start & shut off"? I will crank the engine and it will shut off then if I try to start it again I will have to press the gas while turning the engine over to get it to start, but as soon as I let off the throttle it will go to a low, low RPM and eventually die.

Is there anyway to test and see if it is truly the IAC, like unplugging it or anything like that?

I believe what you guys are saying, and I truly think it is the problem. I just want to cover all my based to see what all the symptoms are of this issue. I don't have a loud WOOO noise coming out from under the hood.

 

You could have more than one problem, like a TPS, or fuel delivery issue too.

The IAC won't likely cause the engine not to start at all, but it sure can affect the idle speed & quality.

Yes you can disconnect the IAC electrical connector, to do a function test, but it'll likely idle rough or maybe stall, IF the IAC is working, so you'd have to open the throttle some to keep the engine running, or from running rough, which is the same thing you've posted that you have to do now, to keep the engine running, when the IAC IS pugged in & is supposed to be working.

So the IAC electrical disconnect test isn't likely to shed much, if any light on your problem, other to say if it responds the same, it's suspect.

My IAC only makes a whoooo noise when I have the A/C on at idle, or at throttle up slightly above idle speed, higher rpm & I can't hear it make noise.

Also check around for vacuum, or intake air leaks & this would include the PCV valve & it's connecting tubing & rubber fittings, the intake air tube After the MAF sensor.

To determine if the fuel pressure is wimpy, try cycling the ignition switch from off to run, (without cranking the engine) three or four times & long enough on, to hear the fuel pump start & run for 2-3 seconds & shut off, in it's computer timed cycle to build fuel pressure, then crank the engine & see if it'll fire, run & idle ok.

If so, suspect a fuel pump, pressure regulator, or filter problem.

More thoughts for consideration, keep us posted.

 

Hmm sounds interesting. Oh I forgot to mention what happened yesterday!

As I was leaving for lunch yesterday. I started the truck and held down the gas to keep the idle up and I was slowly lifting up off the gas the RPMs slowly kept going down...down...down...below 1000 RPMs (almost stalling) then all of the sudden it was like something kicked in and the RPMs came up to a normal idle speed and I didn't have any problems with the truck the rest of the day! Then when I came out to head to work this morning, it was doing this same old crap again...does this sound like the IAC issue?

 

Yup, it does to me.

 

Thanks, I will clean it first and let you know.
I've had the truck for 6 years and put 60,000 miles on it and I have never had to clean it so I would say it is LOOOOOONG overdue.

 

Cleaned the IAC as instructed, still no change. Still idling very hard and stalling out. Almost cut's off as soon as I start it and will not stay on after throttle is released.

 

Could the computer still give me some codes if I took it to an auto parts place, even if the check engine light is not on?

 

It is possible to have "pending" codes stored in the computer, that haven't happened often enough to have the computer turn the CEL on yet.

Many autoparts stores won't scan the computer unless the CEL is lit, but you can fix that by leaving the gas cap loose on the drive over there & that'll turn it on so they'll san it, but you'll know what that code is for!!!! Any port in a storm.....Right!!!! lol

If the working signal from the computer is there & the IAC is fuctioning, but just intermittently sticking/acting out, you won't likely have a code set for it.

The IAC Function test is to disconnect it's electrical connector & if it's functional & working correctly, the engine idle should get worse/slower, or it may even stall. If it does this, the IAC is working & is likely ok.

If there is No change in idle quality with it's electrical connector disconnected, as I posted above, suspect the IAC.

So cleaning the IAC made no difference.
How did it's wiring, electrical connector & pins & sockets look. Any faulty wire insulation, suspect broken wires underneath the insulation, that might show itself as a bulge, or sunken area in the insulation????

Any bent pins, spread sockets, or corrosion on any of them????

With the engine at idle, if you wiggle the IAC electrical connector, or wires to it, or thump the IAC, will the idle change????

You could have other problems, like a vacuum leak, TPS resistance dead spot at the idle position, IAT, or MAF sensor problem, fuel delivery, or idle fuel trim problem, ect.

Without a trouble code, or positive trouble shooting test result, we could guess all day, as many things can cause this problem.

If you have the computer scanned, post All code Numbers found. Keep us posted on your trouble shoot.